Magnet Assembly

ABSTRACT

The present invention provides a receiver comprising a housing, an armature, and a magnet assembly, where the armature and the magnet assembly are arranged in the housing. The magnet assembly comprises a magnet and a magnet shell. The magnet shell forms an inner space in which the magnet is provided, and where at least a part of the armature extends in the inner space. The magnet shell comprises at least two shell parts forming an inner surface encircling the inner space, where each of the shell parts comprises a first and a second end face. The first end face of a first shell part abuts one of the first and second end faces of an adjacent shell part, and the second end face of the first shell part abuts one of the first and second ends faces of an adjacent shell part.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of European Patent ApplicationSerial No. 16207101.3, filed Dec. 28, 2016, which is incorporated hereinby reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to a receiver comprising a magnet assemblycomprising a magnet and a magnet shell. Furthermore, the inventionrelates to a method of manufacturing the receiver, and to the magnetassembly itself.

BACKGROUND OF THE INVENTION

Traditionally, the manufacturing of a receiver comprising a magnetassembly is complicated due to the large number of small parts whichhave to be assembled. Furthermore, the magnetic interface may complicatethe manufacturing process.

Prior art document EP 2 464 141 discloses a transducer assembly with aU-shaped armature. At least a part of the U-shaped armature forms partof the magnet housing.

EP 1 962 551 discloses a moving armature receiver. The receivercomprises a magnet housing being formed partly by legs of the armature.

CN 105 187 987 discloses a magnetic drive mechanism and a receivercomprising the magnetic drive mechanism. The magnet is attached directlyto the receiver housing to omit a magnet shell.

US 2005/140436 discloses a method and a system for assembling ofelectroacoustic transducers. A magnet shell is formed by shell parts andby legs of an E-shaped armature.

US 2011/0311091 discloses an acoustic conversion device comprising ayoke with adjustable size for optimisation of the distance between themagnets.

DESCRIPTION OF THE INVENTION

It is an object of embodiments of the invention to provide an improvedreceiver.

It is a further object of embodiments of the invention to provide animproved manufacturing process.

It is an even further object of embodiments of the invention to providea receiver which facilitate assembling of the receiver and magnetassembly.

According to a first aspect, the invention provides a receivercomprising a housing, an armature, and a magnet assembly, the armatureand the magnet assembly being arranged in the housing, the magnetassembly comprising a magnet and a magnet shell, the magnet shellforming an inner space in which the magnet is provided, wherein at leasta part of the armature extends in the inner space, wherein the magnetshell comprises at least two shell parts forming an inner surfacesubstantially encircling the inner space, and wherein the shell partseach comprises a first and a second end face, the first end face of afirst shell part abuts one of the first and second end faces of anadjacent shell part, the second end face of the first shell part abutsone of the first and second end faces of an adjacent shell part.

Thus, each shell part comprises a first end face and a second end face;i.e. free ends terminating the shell part at opposite ends hereof. Eachshell part further comprising an outer surface part and an inner surfacepart, where the end faces forms an edge arranged in the transitionbetween the outer surface part and the inner surface part. When themagnet shell is assembled by two or more shell parts, each outer surfacepart forms part of the outer surface of the magnet shell, whereas eachinner surface part forms part of the inner surface encircling the innerspace. This is achieved by assembling the shell parts so that each endface of a shell part abuts an end face of an adjacent shell part.

The receiver may be adapted to form part of any personal audio device,such as a hearing aid, such as a Behind-the-Ear (BTE) device, an In theEar (ITE) device, a Receiver in the Canal (RIC) device, aCompletely-in-Canal device (CIC), or any other personal audio device,such as headphones, earphones, and other earpieces. In the context ofthe present invention, the term “hearing aid” shall be understood as adevice which is adapted to amplify and modulate sound and to output thissound to a user, such as into the ear canal of a user.

It should further be understood, that the receiver in one embodiment maybe a balanced armature receiver, whereas the receiver in otherembodiments may also comprise other transducer technologies, such asmoving coil, moving armature, magnetostatic, etc.

Thus, the receiver may be adapted to receive an electrical signal andoutput a corresponding audio signal through a sound outlet.

The receiver comprises a magnet assembly. The magnet assembly isarranged to provide a magnetic field in a gap. The gap may be an air gapor a gap filed with a substance, such as ferromagnetic fluids, dependingon the transducer technology in which the magnet assembly is to be used.The receiver comprises an armature of which at least a part extends inthe inner space; i.e. the armature may comprise at least one legextending at least partly through the gap.

The armature and magnet shell may be made from any type of suitablematerial, such iron and Nickel, capable to guide or carry a magneticflux. Examples of these materials are, but are not limited to thedifferent types of materials mentioned in the ASTM A753 standard. Thematerials may be electrically conducting or not. The armature and themagnet shell may be made of the same material. I should however beunderstood, that the armature and the magnet shell may be made fromdifferent materials.

The receiver may further comprise a diaphragm which is operationallyattached to the armature, such that movement of the armature istransferred to the diaphragm. It will be appreciated that movement ofthe diaphragm causes sound waves to be generated. In one embodiment, thediaphragm is operationally attached to the armature by means of adiaphragm connecting member, such as a drive pin. Alternatively, thediaphragm may itself be attached to the armature.

The diaphragm may comprise a metal material such as aluminium, nickel,stainless steel, or alternatively a plastic material, such as a polymer,e.g. nylon, ABS, acryl, or any other material. It should however beunderstood, that the diaphragm may comprise a plurality of materials.The diaphragm may divide the chamber into two chambers, such as a frontvolume and a back volume.

The receiver may be located in an assembly housing which itself may forma soft shell or which may be located in a shell made of a soft material,such as silicone, to improve comfort of a user. To improve comfortfurther, an individual shell may be made for each user to fit the ear ofthe user. Other suitable materials for the assembly housing may benylon, ABS (plastic), and metals, such as stainless steel, aluminium andtitanium.

A traditional magnet assembly comprises a magnet shell formed in onepiece and forming an inner space in which one or more magnets areprovided. However, positioning of the magnet(s) may be difficult due tothe size and due to requirements and tolerance relating to the magneticinterface.

The inventors have surprisingly found that in contradiction withtraditional practice, it may be possible to provide the magnet shell ofat least two parts. To ensure sufficient magnetic properties of themagnet shell, the magnet shell when assembled of the at least two shellparts should form an inner space having a common inner surface. Or inother words, an inner space being encircled of an uninterrupted surface,and the magnet is provided in that inner space.

In the context of the present invention, the term “uninterruptedsurface” should be understood as a common surface formed by surfaces ofthe at least two shell parts when these are assembled, the surface notbeing interrupted by other elements. As an example, other elements ofthe receiver/magnet assembly may not be inserted in a joint between twoadjacent shell parts. Thus, when assembled the magnet shell forms aseparate element without the inclusion of other parts of the receiver,such as the armature and the housing.

Furthermore, the term “a space being encircled” should be understood asa space being enclosed in, i.e. surrounded by the magnet shell in across-section perpendicular to the magnet. It should further beunderstood, that the inner space may be open at least at one end. I.e.the magnet shell may be ring-shaped, however of arbitrary form, such assquare-shaped or oval.

The term “common surface” should be understood, as a surface beingconstituted by parts of surfaces of the shell parts which together formthe magnet shell.

Thus, the at least two shell parts forms an inner surface beinguninterrupted and encircling the inner space.

By providing the magnet shell by at least two shell parts it may bepossible to attached the magnet to at least one of the shell partsbefore assembling magnet shell, thereby facilitate the assemblingprocedure.

The inner space may have height being defined as the distance between anupper shell part and a lower shell part in a direction substantiallyperpendicular to the armature which at least partly extends in the innerspace. The inner space may define one or more discrete predefinedheights. In one embodiment, only a single height may be defined, as theshell parts may be assembly in only one possible way thereby onlyproviding a single height. In an alternative embodiment, the magnetshell may be assembled in different ways thereby providing two or moreheights of the inner space.

As an example, the latter may be achieved by assembling the magnet shellof two U-shaped shell parts have legs of different length; i.e. a shortleg and a long leg. If the two short legs and the two long legs abut,the height will be different than if each short leg abut a long leg.

To minimise the number of different parts forming the magnet shell, afirst shell part and a second shell part may be substantially identical.It should however be understood, that these shell parts may in anotherembodiment be of different shape. An embodiment comprising a first shellpart and a second shell part being identical may further comprise athird and even a fourth shell part or more of different shape.

It may in one embodiment be an advantage to provide the shell parts ofdifferent shape to compensate for different magnetic resistances, suchas if the armature is a U-shaped armature or if the receiver isconfigured to have the magnetic flux going through the receiver housing.

In one embodiment, the magnet shell comprises two shell parts beingidentical; i.e. having same size and shape. Each of the two shell partsmay be substantially U-shaped; i.e. being formed by two substantiallyparallel legs each being attached to an intermediate portion at an endpart to thereby form a “U”. It should be understood, that each of thetwo U-shaped shell parts may be formed in one piece. Thus, the term“attached to” may also cover elements formed in one piece.

When assembling the magnet shell of the two identical shell parts, theshell parts may abut each other at the free end of the legs; i.e. theend not being attached to the intermediate portion.

Alternatively, each of the two shell parts may be substantiallyL-shaped; i.e. being formed by two legs being attached to each other atan end part and extending there from at an angle of approximately 90degrees to thereby form a “L”. It should be understood, that each of thetwo L-shaped shell parts may be formed in one piece. Thus, the term“attached to” may also cover elements formed in one piece.

When assembling the magnet shell of the two identical shell parts beingL-shaped, the shell parts may abut each other at a side portion of thefree end of the legs; i.e. the ends not being attached to the other leg.It should be understood, that the first and second legs of the L-shapedshell parts may be of different length.

By forming the magnet shell of two substantially identical shell parts,the manufacturing process may be more efficient due to the lower numberof different elements forming part of the receiver. Furthermore,assembling of the receiver may be facilitated, as the assembled magnetshell may be turned upside down without changing the magnet shell andits functionality.

To facilitate handling of the magnet shell, the at least two shell partsmay in one embodiment form a smooth outer surface. In the context of thepresent invention, the term “smooth surface” should be understood as asurface substantially without protrusions and indentations.

The shell parts may have a thickness being defined as a distance fromthe inner surface to an opposite outer surface. In one embodiment, thethickness may be non-uniform along the inner space.

The magnet shell may comprise a protecting layer arranged on the outersurface of the magnet shell. The protecting layer, e.g. a copper layer,may be arranged to reduce electromagnetic radiation from the magnetassembly. The protecting layer may be arranged on the outer surface ofthe magnet shell after assembling of the at least two shell parts.

Additionally or alternatively, a sealing layer may be arranged on theouter or inner surface of the magnet shell after assembling of the atleast two shell parts. The sealing layer may be arranged solely along ajoint of two adjacent shell parts or it may be arranged on a larger partof the outer surface, such as fully covering the outer or inner surface.The sealing layer may be arranged for corrosion protection. As anexample, nano-coating may be used to provide the sealing layer.

The sealing layer may in one embodiment be added in a two-step process.In a first step, the sealing lay may be added as a primer on the magnetshell. In a second step when assembling the receiver, an additionalsealing layer may be added. The additional sealing layer may thenconnect to the primer.

In order to assemble the magnet shell having a common inner surface andthereby an uninterrupted inner surface, the shell parts each comprises afirst and a second end face, i.e. each shell part extends between afirst end face and a second end face. When assembling the magnet shell,the first end face of a first shell part may abut one of the first andsecond end faces of an adjacent shell part. Furthermore, the second endface of the first shell part abuts one of the first and second endsfaces of an adjacent shell part.

Thus, if the magnet shell comprises two shell parts, they are arrangedend face to end face to provide an inner space having a common innersurface; i.e. the first end face of the first shell part abuts thesecond end face of the second shell part and the second end face of thefirst shell part abuts the first end face of the second shell part oroppositely; the first end face of the first shell part abuts the firstend face of the second shell part and the second end face of the firstshell part abuts the second end face of the second shell part.

It should be understood, that if an embodiment comprises three or moreshell parts an end face of a shell part abuts an end face of an adjacentshell part, etc. to provide an inner space having a common innersurface. Thus, the three of more shell parts may be arranged in seriesto provide a common inner surface being an uninterrupted inner surfaceof the inner space.

When assembling the shell parts to form a magnet shell, it may be anadvantage if the tolerances are kept below a threshold value, asassembling e.g. by welding of two adjacent shell parts may befacilitated if the end faces fit each other within a low tolerancelevel. This may be achieved by keeping the roughness of the end face atwhich adjacent shell parts abut below a certain threshold value, e.g. byensuring that the roughness does not exceed 5, 10, or 15 microns as ahigher roughness may increase the risk of air bobbles in the joint. Suchair bobbles should be avoided, or at least the risk of bobbles should beminimized considerably, as bobbles may decrease the magnetic performancedue to discontinuities in the material. The above mentioned thresholdvalues may be especially suitable for receivers having a length in therange of 5-15 mm.

For larger receivers were the contact area of two adjacent shell partsmay be larger, the threshold values may also be larger. Magnetassemblies having a relatively large contact area between two adjacentshell parts may be assembled by a process including pressing the twoshell parts together as this may limit the number of gaps and airbobbles which may be removed when pressing them together, as pressingmay additionally at least partly deform the material from which theshell parts are made.

To facilitate assembling of the magnet shell, the receiver may furthercomprise an alignment structure for alignment of the at least two shellparts.

The alignment structure may form part of the magnet shell, e.g. byforming part of at least one of the shell parts. However, it should beunderstood, that the alignment structure may also be a separate element.As an example, an alignment structure in the form of a separate elementmay be arranged at one of the shell parts, and subsequently the otherone or other ones can be arranged to form the magnet shell while beingsupported by the alignment structure. Thus, in one embodiment, thealignment structure may be in the inner space supporting the shell partsduring assembling. The alignment structure may subsequently be removedagain.

An alignment structure forming part of the magnet shell may as anexample form part of one or more of the end faces of one or more of theshell parts.

It should be understood, that the alignment structure may comprise acombination of a separate element and an element forming part of themagnet shell.

In one embodiment, the alignment structure may comprise a geometricallocking structure forming part of the shell parts. As an example, thegeometrical locking structure may comprise matching indentations andprotrusions on shell parts abutting each other. It should be understood,that the geometrical locking structure may in one embodiment form anindentation at one shell part matching the end face at the other shellpart; i.e. the end face itself may form a protrusion matching anindentation at the other shell part.

The matching indentations and protraction may comprise teeth andcorresponding spaces, where the teeth may be square-shaped, round,serrated, and other similar forms adapted to lock two parts together.

The geometrical locking structure may be formed along the abutting endfaces or transverse to the abutting surfaces.

The magnet may comprise a first magnet portion and a second magnetportion to provide a magnetic field. In one embodiment, the first magnetportion and the second magnet portion may be attached to different shellparts.

The magnet and the magnet portion may be attached to the shell parts bygluing or welding. It should however be understood that other means ofattachment may also be used, such as clamping, screwing or by use of apinhole, etc.

In one embodiment, one magnet portion may be attached by use of onemeans of attachment, whereas another magnet portion may be attached byuse of another means of attachment.

It should be understood, that the magnet/magnet portions may besupported/kept in place by an additional element arranged in the innerspace.

In one embodiment, the invention provides a receiver comprising ahousing, an armature, and a magnet assembly, the armature and the magnetassembly being arranged in the housing, the magnet assembly comprising amagnet and a magnet shell, the magnet shell forming an inner space inwhich the magnet is provided, wherein at least a part of the armatureextends in the inner space, and wherein the magnet shell comprises atleast two shell parts forming an inner surface substantially encirclingthe inner space.

According to a second aspect, the invention provides a method ofmanufacturing a magnet assembly according to the first aspect of theinvention, the method comprising the step of;

-   -   providing a magnet,    -   providing at least two shell parts each comprising a first and a        second end face,    -   providing a housing,    -   providing an armature,    -   assembling the at least two shell parts to form a magnet shell        having an inner space with an inner surface substantially        encircling the inner space, so that the first end face of a        first shell part abuts one of the first and second end faces of        an adjacent shell part, and the second end face of the first        shell part abuts one of the first and second end faces of an        adjacent shell part,    -   attaching the magnet to at least one of the shell parts, and    -   arranging the magnet shell and the armature in the housing.

It should be understood, that a skilled person would readily recognisethat any feature described in combination with the first aspect of theinvention could also be combined with the second aspect of theinvention, and vice versa.

The method according to the second aspect of the invention is verysuitable for the manufacturing of a receiver according to the firstaspect of the invention. The remarks set forth above in relation to thereceiver are therefore equally applicable in relation to the method.

The step of attaching the magnet to at least one of the shell parts maybe carried out prior to the step of assembling the shell parts to form amagnet shell, thereby facilitating attachment of the magnet.

Furthermore, the step of attaching the magnet may comprise a step ofattaching a first magnet portion to a first shell part and a step ofattaching a second magnet portion to a second shell part, as the magnetmay comprise two magnet portions.

In one embodiment, the magnet/magnet parts may be magnetized afterattachment of the magnet/magnet parts to the magnet shell or even afterassembling of the magnet shell.

In another embodiment, the method may comprise a step of magnetizing themagnet prior to the step of assembling the magnet shell.

The step of assembling the magnet shell may comprise a step of gluingthe shell parts together. Additionally or alternatively, the step ofassembling the magnet shell may comprise a step of welding the shellparts together. It should however be understood, that the shell partsmay also be attached to each other my clamping or by other means.

The method may further comprise a step of arranging at least a part ofthe armature in the inner space of the magnet assembly.

As an example, the armature may be T-shaped or U-shaped.

The U-shaped armature may be formed so that each leg extends from and isattached to an intermediate part which forms the bottom of the U.

The T-shaped armature may comprise two elongated parts which in oneembodiment may be of the same length and in an alternative embodimentmay be of different length. Each part extends from a first end to asecond end. One elongated part may be connected to the other elongatedpart at a first distance from the first end and a second distance fromthe second end. The first and second distances may be of the same size.

The first and second part may be formed in one piece. Thus, it should beunderstood that the term “connected to” both covers embodiments wherethe two elongated parts of the T-shaped armature are made as a singleelement, and embodiments where the two elongated parts are made a twoseparate elements which are subsequently attached to each other.

I.e. a T-shaped armature for a receiver of a personal audio device, theT-shaped armature comprising a first elongated part and a secondelongated part, the first and second parts each extending between afirst and a second end, wherein the first end of the first part isconnected to the second part at a first distance from the first end ofthe second part and at a second distance from the second end of thesecond part.

When assembling the receiver, the T-shaped armature may be inserted intoa magnet shell, so that at least the second end of the first part isinserted into the magnet shell, such as into the inner space of themagnet shell.

According to a third aspect, the invention provides a magnet assemblyfor a receiver, the magnet assembly comprising a magnet and a magnetshell, the magnet shell forming an inner space in which the magnet isprovided, wherein the magnet shell comprises at least two shell partsforming an inner surface encircling the inner space, and wherein theshell parts each comprises a first and a second end face, and the firstend face of a first shell part abuts one of the first and second endfaces of an adjacent shell part, the second end face of the first shellpart abuts one of the first and second ends faces of an adjacent shellpart.

It should be understood, that a skilled person would readily recognisethat any feature described in combination with the first and secondaspects of the invention could also be combined with the third aspect ofthe invention, and vice versa.

The features of the receiver according to the first aspect of theinvention are very suitable for the magnet assembly according to thethird aspect of the invention. Furthermore, the method steps accordingto the second aspect of the invention are very suitable for themanufacturing of the magnet assembly according to the third aspect ofthe invention. The remarks set forth above in relation to the receiverand the method are therefore equally applicable in relation to themagnet assembly.

According to a fourth aspect, the invention provides a receivercomprising a housing, an armature, and a magnet assembly, the armatureand the magnet assembly being arranged in the housing, the magnetassembly comprising a magnet and a magnet shell, the magnet shellforming an inner space in which the magnet is provided, wherein at leasta part of the armature extends in the inner space, the magnet shellcomprising at least two shell parts forming an inner surfacesubstantially encircling the inner space, and wherein the magnetassembly comprises an alignment structure for alignment of the at leasttwo shell parts, the alignment structure forming part of the magnetshell.

According to a fifth aspect, the invention provides a receivercomprising a housing, an armature, and a magnet assembly, the armatureand the magnet assembly being arranged in the housing, the magnetassembly comprising a magnet and a magnet shell, the magnet shellforming an inner space in which the magnet is provided, wherein at leasta part of the armature extends in the inner space, and wherein themagnet shell comprises at least two shell parts forming an inner surfacesubstantially encircling the inner space, the shell parts having athickness being a distance from the inner surface to an opposite outersurface, and the thickness being non-uniform along the inner space.

According to a sixth aspect, the invention provides a receivercomprising a housing, an armature, and a magnet assembly, the armatureand the magnet assembly being arranged in the housing, the magnetassembly comprising a magnet and a magnet shell, the magnet shellforming an inner space in which the magnet is provided, wherein at leasta part of the armature extends in the inner space, and wherein themagnet shell comprises two shell parts forming an inner surfacesubstantially encircling the inner space, each of the shell parts beingsubstantially L-shaped in a cross-section.

It should be understood, that the size of the two L-shaped shell partmay be of different size.

According to a seventh aspect, the invention provides a receivercomprising a housing, an armature, and a magnet assembly, the armatureand the magnet assembly being arranged in the housing, the magnetassembly comprising a magnet and a magnet shell, the magnet shellforming an inner space in which the magnet is provided, wherein at leasta part of the armature extends in the inner space, wherein the magnetshell comprises at least two shell parts forming an inner surfacesubstantially encircling the inner space, and wherein at least one ofthe shell parts comprises an indentation formed at an end portion, theindentation forming a shape matching a shape of an end portion ofanother shell part.

According to an eighth aspect, the invention provides a receivercomprising a housing, an armature, and a magnet assembly, the armatureand the magnet assembly being arranged in the housing, the magnetassembly comprising a magnet and a magnet shell, the magnet shellforming an inner space in which the magnet is provided, wherein at leasta part of the armature extends in the inner space, wherein the magnetshell comprises a first and a second shell part, wherein the first shellpart in a cross-section is substantially U-shaped with a first and asecond leg and the second shell part in a cross-section is substantiallyplate-shaped, the plate-shaped shell part having a size which matches adistance between the first and second legs, wherein the shell parts forman inner surface substantially encircling the inner space.

According to a ninth aspect, the invention provides a receivercomprising a housing, an armature, and a magnet assembly, the armatureand the magnet assembly being arranged in the housing, the magnetassembly comprising a magnet and a magnet shell, the magnet shellforming an inner space in which the magnet is provided, wherein at leasta part of the armature extends in the inner space, wherein the magnetshell comprises a first and a second shell part, each shell part in across-section being substantially U-shaped with a first and a second legextending substantially parallel, and extending towards the other shellpart to form an inner surface substantially encircling the inner space,and wherein at least one leg of one shell part forms an overlap with aleg of the other shell part.

According to a tenth aspect, the invention provides a receivercomprising a housing, an armature, and a magnet assembly, the armatureand the magnet assembly being arranged in the housing, the magnetassembly comprising a magnet and a magnet shell, the magnet shellforming an inner space in which the magnet is provided, the armaturebeing T-shaped and at least a part of the armature extends in the innerspace, wherein the magnet shell comprises at least two shell partsforming an inner surface substantially encircling the inner space.

The T-shaped armature may comprise two elongated parts, each partextending from a first end to a second end. One elongated part may beconnected to the other elongated part at a first distance from the firstend and a second distance from the second end. The first and seconddistances may be of the same size.

The T-shaped armature may extend at least partly in the inner space, sothat at least the second end of the first part is inserted into themagnet shell.

The second part of the T-shaped armature may be supported at leastpartly by a shell part; i.e. at least a part of the second part of theT-shaped armature may be arranged in contact with a shell part.

A coil may be arranged in the inner space. In one embodiment, the coilmay be fully encircled by the magnet shell.

It should be understood, that a skilled person would readily recognisethat any feature described in combination with the first and secondaspects of the invention could also be combined with any of the fourth,fifth, sixth, seventh, eighth, ninth, and tenth aspects of theinvention, and vice versa. It should further be understood, that askilled person would readily recognise that any feature described incombination each of the first to tenth aspects of the invention couldalso be combined with any of the first to tenth aspects of theinvention.

The remarks set forth above in relation to the receiver and the methodare therefore equally applicable in relation to any of the receivers ofthe different aspects.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be further described withreference to the drawings, in which:

FIGS. 1A-1B illustrate two different views of an embodiment of a magnetassembly and an armature,

FIGS. 2A-2E illustrate different views of an embodiment of a magnetassembly, an armature, and a coil,

FIGS. 3A-3Q illustrate different embodiments of a magnet assembly, and

FIG. 4 illustrates a further alternative of an embodiment of a magnetassembly.

DETAILED DESCRIPTION OF THE DRAWINGS

It should be understood that the detailed description and specificexamples, while indicating embodiments of the invention, are given byway of illustration only, since various changes and modifications withinthe spirit and scope of the invention will become apparent to thoseskilled in the art from this detailed description.

FIGS. 1A-1B illustrate two different views of an embodiment of a magnetassembly 1 and an armature 2 for a receiver. The magnet assembly 1comprises a magnet 4 and a magnet shell 5. The magnet shell 5 forms aninner space 6 in which the magnet 4 is provided.

The magnet shell 5 comprises in the illustrated embodiment two shellparts 5A, 5B forming a common inner surface 7 encircling the inner space6.

The magnet shell 5 may comprises a protecting layer (not shown) arrangedon the outer surface of the magnet shell. The protecting layer, e.g. acopper layer, may be arranged to reduce electromagnetic radiation fromthe magnet assembly 1.

The armature is U-shaped and a first leg 8 extends through the innerspace 6 formed by the magnet shell 5. A second leg 9 of the U-shapedarmature extends substantially parallel to the first leg 8.

The receiver may further comprise a diaphragm (not shown) which isoperationally attached to the armature 2, such that movement of thearmature 2 is transferred to the diaphragm 10. The receiver may comprisea drive pin operatively attaching the diaphragm to the armature 2.Movement of the diaphragm will cause sound waves to be generated.

FIGS. 2A-2D illustrate different views of an alternative embodiment of amagnet assembly 101, a T-shaped armature 102, and a coil 112. The magnetassembly 101 comprises a magnet 104 and two shell parts 105A, 105Bforming a common inner surface 107 encircling an inner space 106.

FIG. 2A illustrates the different elements unassembled. In FIG. 2B, thetwo shell parts 105A, 105B are assembled to form the common innersurface 107 encircling the inner space 106.

The shell parts 105A, 105B may comprises a protecting layer (not shown)arranged on the outer surface of the magnet shell; i.e. a protectivelayer may be arranged on top of the upper shell part 105A and on thebottom of the lower shell part 105B. The protecting layer, e.g. a copperlayer, may be arranged to reduce electromagnetic radiation from themagnet assembly 105.

The protective layer 105A′ arranged at the upper shell part 105A isillustrated by the hatching in FIG. 2E. It should be understood, thatthe protective layer may be a primer, a nano-coating, a copper layer, oranother shielding material.

The shell parts 105A, 105B each comprises a first joining surface 113and a second joining surface 114. When assembling the magnet shell 105,the first joining surface 113A of the first shell part 105A abut thefirst joning surface 113B of the second shell part 105B, and secondjoining surface 114A of the first shell part 105A abuts the secondjoining surface 114B of a second shell part 105B. The joining surfaces113, 114 may as an example be brought together by pressing and deformingthe material, such as metals, from which the shell parts 105A, 105B aremade.

In FIG. 2C, the coil 112 has been inserted into the inner space 106formed by the two shell parts 105A, 105B.

The T-shaped 102 armature comprises two elongated parts, each partextending from a first end to a second end. The lower elongated part isconnected to the upper elongated part substantially at the middle of theupper elongated part.

In FIG. 2D, the T-shaped armature 102 has been inserted into the innerspace 106 formed by the two shell parts 105A, 105B so that the lowerpart extends through the inner space 106 whereby an end portion 102Aextends on the opposite side of the inner space. A drive pin can beattached to the end portions 102A.

The upper part of the T-shaped armature is supported at least partly bythe shell part 105B, whereby at least a part of the upper part of theT-shaped armature 102 is arranged in contact with the shell part 105B asalso illustrated in FIG. 2D.

FIGS. 3A-3M illustrate different embodiments of a magnet assembly 201,301, 401, 501, 601, 701, 801.

In FIG. 3A, the magnet assembly 201 comprises a magnet 204 comprisingtwo magnet portions 204A, 204B and two shell parts 205A, 205B forming acommon inner surface 207 encircling an inner space 206.

The shell parts 205A, 205B each comprises a first end face 213 and asecond end face 214. The end faces 213, 214 abut each other in a joint215 being parallel to the magnet portions 204A, 204B substantiallycentrally in a direction along the height of the magnet assembly 201.

In the illustrated embodiment, the shell parts 205A, 205B aresubstantially identical, both being U-shaped.

In FIG. 3B, the magnet assembly 301 comprises two magnet portions 304A,304B and two shell parts 305A, 305B forming a common inner surface 307encircling an inner space 306.

In the illustrated embodiment, the shell parts 305A, 305B are ofdifferent shape, as the upper shell part 305A is a substantially flatelement, whereas the lower shell part 305B is U-shaped.

The shell parts 305A, 305B each comprises a first end face 313 and asecond end face 314. The end faces 313, 314 abut each other in a joint315 being parallel to the magnet portions 304A, 304B along the lowersurface of the upper shell part 305A.

In FIG. 3C, the magnet assembly 401 is similar to the embodiment of FIG.3A. However, the end faces 413, 414 abut each other in a joint 415 beingtransverse to the magnet portions 404A, 404B substantially centrally ina direction along the height of the magnet assembly 401.

By providing the end faces 413, 414 so that they extend transverse tothe shell parts 405A, 405B, the area of the end faces are larger wherebythe area of the joint 415 are larger than the area of the joint 215 ofthe embodiment illustrated in FIG. 3A.

In FIG. 3D, the magnet assembly 501 comprises two magnet portions 504A,504B and two shell parts 505A, 505B forming a common inner surface 507encircling an inner space 506.

In the illustrated embodiment, the shell parts 505A, 505B aresubstantially identical. The end faces 513, 514 are formed at a portionof the shell parts 505A, 505B extending toward the centre of the innerspace 506.

In FIG. 3E, the magnet assembly 601 is similar to the embodimentsillustrated in FIG. 3A and 3C. However, the end faces 613, 614 abut eachother in a joint 615 substantially centrally in a direction along theheight of the magnet assembly 601.

The end faces 613, 614 are each provided with a plurality of teeth 616,617 which form a geometrically locking structure keeping the two shellparts 605A, 605B in a fixed position relative to each other. The teeth616 of the upper shell part 605A are inserted into spaces of the lowershell part 605B, whereas the teeth 617 of the lower shell part 605B areinserted into spaces of the upper shell part 605A.

In FIG. 3F, the magnet assembly 701 is similar to the embodimentsillustrated in FIG. 3A, 3C, and 3E. However, the shell parts 705A, 705Bwhich abut each other in a joint 715 substantially centrally in adirection along the height of the magnet assembly 701 each forms astep-shaped end portion 713, 714 thereby forming a geometrically lockingstructure which partly fixes the two shell parts 705A, 705B to eachother.

In FIG. 3G, the magnet assembly 801 comprises two magnet portions 804A,804B and two shell parts 805A, 805B forming a common inner surface 807encircling an inner space 806.

In the illustrated embodiment, the shell parts 805A, 805B aresubstantially identical, both being U-shaped.

However, instead of joining the shell parts 805A, 805B at the first andsecond end faces, the shell parts 805A, 805B are inserted into eachother, so that one leg 818 of each of the U-shaped shell parts 805 islocated in the inner space, and so that the other leg 819 is locatedoutside the inner space 806. The overlapping areas along the legs 818,819 increase the connection area of the two shell parts 805A, 805B.

FIG. 3H, the magnet assembly 901 comprises two magnet portions 904A,904B and two shell parts 905A, 905B forming a common inner surface 907encircling an inner space 906. At one side, the magnet shell 905 isassembled by inserting one leg 918 of the U-shaped shell part 905B inthe inner space, and by locating one leg 919 of the U-shaped shell part905A outside the inner space 906. At the other side, the magnet shell905 is assembled at the end faces 913A which extend away from the innerspace 906.

FIGS. 31 and 3J illustrate two similar embodiments of a magnet assembly1001, 1101 each comprising two L-shaped shell parts 1005A, 1005B, 1105A,1105B. The embodiment 1101 illustrated in FIG. 31 comprises two L-shapedshell part 1005A, 1005B of same size, whereas one of the L-shaped shellparts 1105A in FIG. 3J is larger than the other L-shaped shell part1105B. By provided the L-shaped shell parts 1105A, 1105B of differentsize, the shape may assist when assembling the shell parts since theyare at least partly self-assigning.

In FIG. 3K, the magnet assembly 1201 is similar to the embodimentillustrated in FIG. 3G. However, the thickness of the legs 1218, 1219are approximately only half the thickness of the legs 818, 819 therebyreducing the total thickness of the magnet shell 1205 in the overlapbetween the legs 1218, 1219.

In FIG. 3L, the magnet assembly 1301 is similar to the embodimentillustrated in FIG. 3H. However, the thickness of the legs 1318, 1319are approximately only half the thickness of the legs 918, 919 therebyreducing the total thickness of the magnet shell 1305 in the overlapbetween the legs 1318, 1319 at the right side of the magnet shell 1305.

In FIG. 3M, the magnet assembly 1401 is similar to the embodimentillustrated in FIG. 31. However, at one of the end parts the thicknessof the shell parts 1405A, 1405B is reduced to approximately half thethickness of the remaining shell part. The reduced thickness willfacilitate alignment of the two shell parts 1405A, 1405B as the otherend part will fit into the indentation provided by the reducedthickness.

In FIG. 3N, the magnet assembly 1501 is similar to the embodimentillustrated in FIG. 3J. However, at one end part the thickness of theshell part 1505A is reduced to approximately half the thickness of theremaining shell part. The reduced thickness will facilitate alignment ofthe two shell parts 1505A, 1505B as one end part of the shell part 1505Bwill fit into the indentation provided by the reduced thickness of theshell part 1505A.

In FIG. 3O, the magnet assembly 1601 is similar to the embodimentillustrated in FIG. 3A. However, the end faces 1613, 1614 abut eachother in joints 1615′, 1615″ at different heights of the magnet assembly601, since the legs 1618, 1619 are of different length. When assembledas illustrated in FIG. 3O, the assembled magnet assembly 1601 isidentical to the magnet assembly illustrated in FIG. 3A.

However, if the lower a shell part 1605B is rotated 180 degrees asindicated by the arrow A, the two long legs 1619 will join each other,while the two short legs 1618 will join each other. This will change theeffective distance between the magnet portions 1604A, 1604B and therebythe magnet characteristics of the magnet assembly.

In FIG. 3P, the magnet assembly 1701 is similar to the embodimentillustrated in FIG. 3A. However, the end faces 1713, 1714 abut eachother in a joint 1715 being arranged substantially centrally along thewidth of the magnet portions 1704A, 1704B; i.e. a vertically splitmagnet shell. Since the magnet portions 1704A, 1704B overlap the joints1715, the required tolerances with regard to the assembling of the shellparts can be lowered.

In FIG. 3Q, the magnet assembly 1801 is similar to the embodimentillustrated in FIG. 3B. The shell parts 1805A, 1805B are of differentshape, as the left shell part 1805A is a substantially flat element,whereas the right shell part 1805B is U-shaped. The left shell part1805A may form part of the armature thereby providing the ability of asmaller receiver. Preferably the armature may be U-shaped.

The end faces 1813, 1814 abut each other in a joint 1815 beingperpendicular to the magnet portions 1804A, 1804B along the innersurface of the left shell part 1805A.

FIG. 4 illustrates a further alternative of an embodiment of a magnetassembly 1901, in which the magnet shell comprises three shell parts1905A, 1905B, 1905C. The upper shell part 1905A and the lower shell part1905B being joined by an intermediate shell part 1905C.

A magnet portion 1904A, 1904B is attached to each of the upper and lowershell part 1905A, 1905B.

1. A receiver comprising a housing, an armature, and a magnet assembly,the armature and the magnet assembly being arranged in the housing, themagnet assembly comprising a magnet and a magnet shell, the magnet shellforming an inner space in which the magnet is provided, wherein at leasta part of the armature extends in the inner space, wherein the magnetshell comprises at least two shell parts forming an inner surfacesubstantially encircling the inner space, and wherein the shell partseach comprises a first and a second end face, and the first end face ofa first shell part abuts one of the first and second end faces of anadjacent shell part, the second end face of the first shell part abutsone of the first and second ends faces of an adjacent shell part.
 2. Areceiver according to claim 1, wherein each shell part further comprisesan outer surface part and an inner surface part, the end faces formingan edge arranged in the transition between the outer surface part andthe inner surface part, wherein each outer surface part forms part ofthe outer surface of the magnet shell and each inner surface part formspart of the inner surface encircling the inner space, when each end faceof a shell part abuts an end face of an adjacent shell part.
 3. Areceiver according to claim 1, further comprising an alignment structurefor alignment of the at least two shell parts.
 4. A receiver accordingto claim 3, wherein the alignment structure forms part of the magnetshell.
 5. A receiver according to claim 3, wherein the alignmentstructure comprises an indentation formed at an end portion of at leastone of the shell parts, the indentation forming a shape matching a shapeof an end portion of another shell part.
 6. A receiver according toclaim 3, wherein the alignment structure comprises a geometrical lockingstructure forming part of the shell parts.
 7. A receiver according toclaim 1, wherein the magnet comprises a first magnet portion and asecond magnet portion, the first magnet portion and the second magnetportion being attached to different shell parts.
 8. A receiver accordingto claim 1, wherein the shell parts have a thickness being a distancefrom the inner surface to an opposite outer surface, the thickness beingnon-uniform along the inner space.
 9. A method of manufacturing a magnetassembly according to claim 1, the method comprising the step of;providing a magnet, providing at least two shell parts each comprising afirst and a second end face, providing a housing, providing an armature,assembling the at least two shell parts to form a magnet shell having aninner space with an inner surface substantially encircling the innerspace, so that the first end face of a first shell part abuts one of thefirst and second end faces of an adjacent shell part, and the second endface of the first shell part abuts one of the first and second end facesof an adjacent shell part, attaching the magnet to at least one of theshell parts, and arranging the magnet shell and the armature in thehousing.
 10. A method according to claim 9, wherein the step ofattaching the magnet to at least one of the shell parts is carried outprior to assembling the shell parts to form a magnet shell.
 11. A methodaccording to claim 10, wherein the step of attaching the magnetcomprises a step of attaching a first magnet portion to a first shellpart and a step of attaching a second magnet portion to a second shellpart.
 12. A method according to claim 9, comprising a step ofmagnetizing the magnet prior to the step of assembling the magnet shell.13. A method according to claim 9, wherein the step of assembling themagnet shell comprises a step of gluing the shell parts together.
 14. Amethod according to claim 9, wherein the magnet is attached to one ofthe shell parts prior to a step of releasing the shell part from acarrier material to which it is attached during manufacturing of theshell part.
 15. A magnet assembly for a receiver according to claim 1,the magnet assembly comprising a magnet and a magnet shell, the magnetshell forming an inner space in which the magnet is provided, whereinthe magnet shell comprises at least two shell parts forming an innersurface substantially encircling the inner space, and wherein the shellparts each comprises a first and a second end face, and the first endface of a first shell part abuts one of the first and second end facesof an adjacent shell part, the second end face of the first shell partabuts one of the first and second ends faces of an adjacent shell part.16. A receiver according to claim 4, wherein the alignment structurecomprises an indentation formed at an end portion of at least one of theshell parts, the indentation forming a shape matching a shape of an endportion of another shell part.
 17. A receiver according to claim 2,wherein the magnet comprises a first magnet portion and a second magnetportion, the first magnet portion and the second magnet portion beingattached to different shell parts.
 18. A magnet assembly for a receiveraccording to claim 2, the magnet assembly comprising a magnet and amagnet shell, the magnet shell forming an inner space in which themagnet is provided, wherein the magnet shell comprises at least twoshell parts forming an inner surface substantially encircling the innerspace, and wherein the shell parts each comprises a first and a secondend face, and the first end face of a first shell part abuts one of thefirst and second end faces of an adjacent shell part, the second endface of the first shell part abuts one of the first and second endsfaces of an adjacent shell part.
 19. A method according to claim 10,comprising a step of magnetizing the magnet prior to the step ofassembling the magnet shell.
 20. A method according to claim 10, whereinthe magnet is attached to one of the shell parts prior to a step ofreleasing the shell part from a carrier material to which it is attachedduring manufacturing of the shell part.